He spent nights searching for lost wallets between cars in the parking lot outside Sam Houston Race Park. Crawling the tile floors for discarded betting slips. Begging for change from the ladies at the concession stand.

"I did things that people with any pride wouldn't do," Kanuch says. "Anything to scrape enough money for a bet."

It's a Friday evening. The rains have cleared and the track is packed with young families and cruising teenagers, giving it the air of a suburban mall.

Kanuch points out the regulars, who sit alone with pencils poised, bifocals slid to the tips of their noses, eyes glued to the televised simulcast races. Like working stiffs, they hunch over the long, narrow tables, papers spread out before them.

Kanuch knows them because he was one of them. He clocked many 14-hour days at the track -- placing bets, he says, "from bell to bell."

It was a job, and a burdensome one at that.

"I could see I was destroying my life," he says, "but I couldn't stop."

And he couldn't see why.

After all, until a few years ago the 51-year-old Kanuch had visited casinos and racetracks only a half-dozen times in his life, never losing more than a couple hundred bucks. Even when he played poker with pals, the ante was 25 cents and the pot rarely exceeded a few singles.

He had a life -- a good life. A wife of 20 years. Two sons. Family vacations. A high-paying job at Texaco. A big house in a suburb northwest of Houston.

In 1993 Kanuch was diagnosed with Parkinson's disease, forcing him to slow down. But the illness didn't get him down. He's not the depressive type.

"I'm just an even-keel, somewhat studious, fun-loving, easy-to-get-along-with type of person," he says.

The compulsion to gamble struck suddenly, inexplicably, six years ago. And there were other changes in his behavior.

Sexual urges overwhelmed him. He began to demand intercourse from his wife five, six times a day. He tried to perform throughout the night -- night after night.

He cried as he watched a media report that described a new medical study showing a link between compulsive, self-destructive behavior and drugs prescribed to Parkinson's patients. In a small segment of users, the medications affected areas of the brain in ways similar to cocaine, methamphetamine and heroin.

People who had never gambled before were suddenly wagering all their savings. People who had never cheated on their spouses were secretly acting out sexual fantasies with multiple partners. People who had never had weight problems were packing on as much as 50 pounds in a matter of months.

Kanuch took solace that he wasn't alone. That somehow he really wasn't to blame for his behavior. And, most heartening of all, that his compulsions would disappear after he was weaned off the medication.

But by then it was too late.

The typical Parkinson's patient is no thrill-seeker. He's risk-averse and exhibits a rigid, focused personality. He doesn't gamble. He isn't hypersexual. He doesn't bungee-jump or skydive. He doesn't drink, smoke or do drugs.

For him, there's no real high in getting high.

That's because Parkinson's patients suffer from a dopamine deficiency in the brain. The lack of dopamine -- a chemical that transmits messages from one brain cell to another -- affects body movement, causing classic symptoms such as joint stiffness, tense muscles, a stooped posture, a shuffling gait and tremors.

Also, though such effects are less widely known and understood, low dopamine levels can limit emotional responses and the ability to experience pleasure and pain.

So neurologist Mark Stacy knew something was fishy when in 1998 he examined two Parkinson's patients in the same week whose spouses complained that their husbands had gambled away some $60,000 each since their last visit with him just three months earlier. Both of these patients were taking dopamine agonists -- a class of new FDA-approved drugs used to mimic the role of dopamine.

During the next year Stacy conducted a study of nearly 1,900 patients, most of whom were prescribed dopamine agonists. Of these, he identified nine patients with no prior history of gambling problems who developed gambling addictions while on the drugs. In seven of those cases, the gambling began within weeks of starting the dosage. One of these patients committed suicide apparently after gambling herself into huge debt.

Stacy also reported that the urge to gamble dissipated in patients as they were weaned off the medications.

Despite the evidence, Stacy says, he was reluctant to publish his findings. He reasoned that the drugs led to pathological behavior in a mere tiny percentage of patients. That the drugs worked extremely well for others who didn't suffer from such side effects. And that the drugs had some major benefits over levodopa, long the gold standard in Parkinson's treatment.

"I fretted and kind of rocked back and forth on the observation," says Stacy, director of the Movement Disorders Clinic at Duke University. "I didn't want to create a false uproar."

Prompted by colleagues, Stacy eventually published his findings in the journal Neurology in August 2003.

The study led to an outpouring of media attention. Stacy received thank-you letters and testimonials from Parkinson's patients from across the country and around the world whose lives were upended after taking the dopamine agonists. Relationships were destroyed, families ripped apart by financial ruin, infidelity and divorce.

In July psychologist M. Leann Dodd of the Minnesota-based Mayo Clinic published a report in the Archives of Neurology that took the Stacy study a step further. During a two-year span Dodd treated 11 Parkinson's patients who became pathological gamblers. In nine of those cases, the patients were prescribed the dopamine agonist Mirapex, or pramipexole dihydrochloride. Mirapex, in particular, Dodd found, had the greatest potential to wreak havoc on the brain's limbic system -- the area related to pleasure, mood and disinhibition.

The Dodd study could have dire consequences for the once-touted wonder drug. Mirapex, since receiving FDA approval in 1997, has fast become one of the top-selling Parkinson's drugs on the market, recording more than $200 million in U.S. sales alone for the last several years. It's also among the most heavily marketed Parkinson's drugs, according to neurologists who say they are deluged by free samples and brochures.

Unlike Stacy, Dodd included in her report the extent of personal damages suffered by these patients. They included a 52-year-old married man who gambled away $100,000, gained 50 pounds, became addicted to pornography and engaged in extramarital affairs; a 68-year-old married man who lost $200,000 at casinos in just six months and became hypersexual, "leaving town for days without anyone knowing his whereabouts"; and a 54-year-old married pastor who began to gamble daily and kept the addiction a secret from his wife.

"What actually triggers the patient to take that first walk into the casino or to have that first affair, I don't really know what is doing that," Dodd says. "But once the behavior stimulates this reward area, it becomes so important to get the reward over and over and over again.

"It's much like a drug addiction -- like people who take cocaine or meth and have to go back and get more and more and more."

The Stacy and Dodd studies triggered a pair of class-action lawsuits based in Canada and Southern California. These suits allege that pharmaceutical giants Boehringer Ingelheim Pharmaceuticals Inc., which manufactures Mirapex, and Pfizer Inc., which co-markets Mirapex, failed to warn doctors and patients that taking the drug could lead to pathological behavior.

Earlier this year, Boehringer Ingelheim added a new warning to the "Important Product Information" section on its Mirapex Web site, citing "compulsive behaviors (including sexual and pathological gambling)" as possible side effects. But critics say the seven-word phrase, buried on page 17 of a 21-page technical document, is insufficient warning.

"That's not a warning label -- it's a joke," says Daniel Kodam of Soheila Azizi & Associates, lead attorney in the California-based class-action suit. "This is something that should have been discovered in the clinical trials."

A Pfizer spokeswoman declined to comment on the suit; Boehringer Ingelheim didn't respond to several phone calls.

Kodam says he's been "bombarded" by testimonials from affected Mirapex patients since the Dodd report was released. The number of plaintiffs represented in the class-action suit has more than doubled and now comprises some 400 people from across the country, including two dozen Texans.

"We suspect the number of people affected is in the thousands," Kodam says.

Plaintiffs include Peggy Andressen, 51, from Seattle, Washington, who claims she opened accounts at more than 60 online casinos, losing some $1.2 million in four years; Alan Hahn, 56, a financials trader from Schaumburg, Illinois, who says he not only bankrupted himself but also gambled away more than $250,000 entrusted to him by clients; and David Neal, 58, from Palm Springs, California, who says he drove to casinos as many as 12 times a day, losing $250,000 in six weeks.

All of these patients say they had never suffered an addiction, gambling or otherwise, until they were prescribed Mirapex.

The Stacy and Dodd studies have received much publicity. But other, more obscure reports linking Parkinson's medications to bizarre, compulsive behaviors date back to the mid- to late '90s.

For instance, about a year before the Stacy study appeared, neurologists in Ecuador reported that four patients developed pathological gambling addictions, anxiety disorders and obsessive-compulsive disorders after taking levodopa for more than eight years. They included a 50-year-old man who began showering seven times a day and a 64-year-old woman who brushed her hair for hours every day because "she felt as if her hair was slithering on her head."

One 71-year-old man, the report stated, developed "an intense preoccupation with the presence of ants in his apartment. He spent several hours daily hunting them by spraying insecticides or placing poison on every corner; he said that if he did not kill them, they would swallow him up. It was not uncommon for him to wake up at midnight and go hunting ants or suddenly start doing so while he had visitors. If someone tried to stop him by reasoning with him about his absurd behavior he scratched vigorously all over his body."

While strange, such behavior was largely benign. In contrast, the most extreme reports from Mirapex users include people driven to commit suicide, rape and possibly even murder.

Two summers ago central Pennsylvania resident Robert Sealy beat his wife to death while under the influence of Mirapex. Last month the Sealy family sued his doctor for increasing the drug's dosage despite changes in his behavior that included chasing his wife around their property with a running chain saw.

Wayne Kanuch doesn't remember much about the accident. One early evening last October, he says, "I was driving home, heading south on Mason Road just off of I-10 to Cimmaron Parkway, when I just nodded off fell asleep at the wheel."

"I was wide awake, alert. And then, just like that," he explains, snapping his fingers, "I was just gone, out like a light."

He "woke up out of this state" to find his Toyota pickup truck smashed into the back end of a Jeep occupied by two young women and two small children. Fortunately, no one was injured.

By the time of the accident, Kanuch had been taking Mirapex for five years. And his life had completely changed.

His wife was already long gone. She divorced him and took their sons with her. They sold their $200,000 home in Copper Lakes, and she remarried a couple of years later.

Kanuch was fired from his $85,000-a-year job at Texaco. Once hailed as a strong performer, Kanuch became an employer's nightmare.

He scanned Internet porn and adult dating services at his desk. Spent three-hour lunch breaks in Houston's downtown tunnels pumping thousands of dollars into Texas Lottery scratch-off tickets. Called in sick and headed to the track. And maxed out the corporate credit card betting on horses.

He landed jobs at Paradigm Technologies, Inc., Mosbacher Energy Co., Marathon Oil Corp. and Meridian Resource Corp. But all were short-lived, lasting months or even days.

He couldn't keep an apartment, either. After losing his home he was evicted five times from five landlords in five years.

Kanuch still found ways to score women. It helped that he's six foot five, charming and a good country-western dancer with strawberry blond hair.

He started an affair with a businesswoman from Katy. She thought she had found her mate, so she let him move in. His credit was in the toilet, so she agreed to co-sign on a new Toyota pickup for him. He totaled the truck and Jeep several months later. She got stuck paying the $28,000 bill.

By then, she had already ended their two-year relationship.

Looking back, she says their time together was "hell."

He kept her awake at night pleading for sex. Stayed up late ogling Internet porn. Hid his gambling from her. And even abused her credit cards after she "foolishly let slip my PIN number."

"The lies, the deceitfulness," were "very hard to take."

Kanuch moved into yet another rental apartment in Katy. Several weeks had passed when she got a phone call from him.

"He sounded desperate, upset, as if he was crying," she recalls.

She feared he might be suicidal, so she drove over to comfort him.

"I didn't realize what I was stepping into," she says.

"He tried to physically rape me. But I was able to get away. I did not call the police like I probably should have at the time."

It's not just men who have become sex addicts while taking Mirapex.

Ann (not her real name) is a social worker in a small Midwestern college town. She's 39, married 17 years, with three kids ages six to 21.

Three years ago Ann was diagnosed with restless legs syndrome, a relatively common disorder that afflicts 10 percent of the population. Side effects include a persistent urge to move the legs, which usually worsens at night. RLS is likely caused by low levels of iron in regions of the brain that produce dopamine; it's treated with the same medications used by Parkinson's patients.

Ann says her behavior began to change a few months after taking her doctor-prescribed daily regimen of Mirapex.

She used to visit casinos recreationally maybe once a year with her husband. Now the urge to gamble gripped her daily. She bought batches of scratch-off lottery tickets and drove two hours, across state lines, to get to the nearest riverboat.

An avid seamstress, she spent money set aside for groceries on reams of sewing material that she didn't need and would never use. She began projects late at night and worked on them until dawn.

Most distressing of all, she "all of a sudden started to have these incredibly lewd fantasies." She says that until then she'd always been faithful to her husband. That their sexual relationship was healthy and satisfying.

"I never even dreamed of having an affair," she attests. "I couldn't believe people would actually do something like that outside of their marriage.

"I was in a completely monogamous relationship, knowing until the day I die my husband would be the only person I would be with."

When her husband went to bed, Ann went to the computer. She surfed Internet porn sites and met people in adult chat rooms. She masturbated while having phone sex and cybersex with dozens of anonymous men.

"I did not even realize that I could talk and act in such vulgarity," she says. "I have never talked to my husband in such graphic details as I did to perfect strangers."

Ann began a string of flings, acting out her fantasies with people she met online. For the first time in her life, she had sex with a woman, a couple and two men at once. She had sex in seedy places, giving blow jobs through glory holes in adult bookstores.

"Meeting someone in a hotel room, a stranger -- that's a whore," she says. "But I wanted to do it. I can't even explain why I wanted to do it."

As she continued these affairs, Ann developed emotional attachments to at least two men that went on for a year.

She "lied countless times" to her husband, family, friends and employer. She borrowed money to pay bills and instead used it to gamble. She traveled hours away for weekend-long sex romps, telling her husband she was attending business conferences.

"You learn to be very secretive and unfortunately you become a very good bullshitter," she explains.

Ann's husband complained that she'd become emotionally detached. That he was forced to take on extra jobs because of her frivolous spending habits. That she was not meeting his sexual needs.

But she continued her behavior until a couple of months ago, when he served her with divorce papers.

Several weeks later, Ann saw a media report announcing the Dodd study. She immediately asked her doctor to take her off the Mirapex.

Though fully off the medication for just a few weeks, Ann says, the compulsions have already vanished. A friend recently invited her to a casino, but she declined.

Ann hasn't told anyone else about her promiscuity. She vows to never tell her husband.

"I can't share my pain with anybody," she says. "I have to keep it to myself. The same thing with the whole gambling thing. I lose all this money and leave the parking lot completely disgusted with myself. But I can't talk to anybody about it. It's a very lonely feeling."

Ann says she's become confused. That she's reluctant to trash all her trashy e-mails because while "it brings back some painful memories, it also brings back some good times."

"It's a thrill when somebody new thinks you're sexy," she says. "But if I want to continue on and really be sincere in my marriage, I have to get rid of the evidence."

She says months have passed since her last affair. That she wants to devote herself again to her husband and family. That while having sexual fantasies may be normal, she regrets ever crossing the line to live them out.

"It took me to the lowest level of my life," she says. "It destroyed me emotionally."

Five years ago, neurologists joked that dopamine agonists used by some Parkinson's patients "increased their libido -- almost a little too much," according to Dr. Mya Schiess, a movement disorder specialist at the University of Texas-Houston Medical School.

"Attention should have been made to that," Schiess says, "because it was probably a comment on hypersexuality."

She adds: "One thing that all treating physicians learn real quick is that you can get addicted to dopamine."

And yet Wayne Kanuch's neurologist claims he had no idea.

Katy-based Dr. Jose Diaz told Kanuch earlier this year -- after the deluge of media reports spawned by medical studies warning against Mirapex -- that no correlation existed between the medication and his sex and gambling addictions.

"Even among neurologists it's not well known," says Diaz, whose office is located above a Comerica Bank on South Mason Road.

Diaz also claims he had no idea that driving while on Mirapex can prove hazardous.

"It's very unusual to have a sleep attack," Diaz says.

In fact, it isn't.

In 1999 a New York doctor published a report in Neurology citing eight men who suffered car accidents from narcolepsy-like sleep attacks while taking Mirapex.

This led to a change in Mirapex's labeling, which now states that "somnolence is a common occurrence in patients receiving Mirapex" and that some patients "perceived that they had no warning signs such as excessive drowsiness, and believed that they were alert immediately prior to the event."

Kanuch had to educate and convince his doctor about these well-publicized, destructive side effects before being weaned off Mirapex. Kanuch pointed Diaz to the Stacy study and a Web site (www.loveandcasinowar.com/blogarch/000267.php) loaded with testimonials from people whose lives changed dramatically while on Mirapex.

Even after this, Diaz let months pass before scheduling Kanuch for an appointment.

"It's urgent," Diaz told me, "but it's not an emergency."

Let's review: While on Mirapex Kanuch lost his wife and family, his home, his job, his savings, suffered a car crash and attempted to rape his ex-lover. That would seem to constitute an emergency.

To this, Diaz says, Kanuch should have "taken some responsibility for his own behavior."

Other neurologists say such a comment belies a lack of even the most elementary understanding of addictions.

"They're overstimulated," Schiess says. "They don't have any control over stopping it."

Dodd from the Mayo Clinic says she has received some criticism regarding her study. That people who exhibited such behavior on Mirapex made decisions and must account for their actions. It's the typical you-make-your-bed-you-lie-in-it argument.

"I believe people have free will," Dodd contends, "but I also believe people are driven to do things that they're not necessarily wanting to do."

Dr. Timothy Fong, associate professor of psychology at UCLA's Neuropsychiatric Institute, likens Mirapex to cocaine, which "releases a huge outpouring of dopamine levels," thereby causing an intense heightening in the brain's pleasure senses. Mirapex, he says, "increases the sensitivity of dopamine receptors," creating a similar sense of euphoria.

The Dodd and Stacy studies likely won't lead to new frontiers in understanding Parkinson's disease. But experts such as Fong say they "open a window into the world of addictions in general."

"These people were chemically induced to have compulsive behavior," says Fong, who is also co-director of UCLA's Gambling Studies Program. "When we can manipulate that kind of chemical, then we can really begin to understand compulsive behavior."

Fong says that researchers are now seeking to understand why some people suffer these side effects on Mirapex, while others do not. In the meantime, he hopes the studies help to legitimize pathological gambling as a psychiatric disorder in the eyes of the federal and state governments -- which provide scant funding to treat and research the illness.

"Behavioral addictions are not bullshit," Fong says. "They can be neurobiologically driven."

Back at Sam Houston Race Park, Wayne Kanuch complains of feeling claustrophobic. He says his stomach is in knots.

A man takes him by the arm, asks where he's been, why he doesn't come around anymore. Kanuch shrugs and turns away.

Kanuch walks outside to the track, passes a barbecue stand and leans against a metal fence.

"Right now the idea of gambling is foreign to me," he says. "I have no interest in it."

Kanuch hasn't gambled since he was taken off Mirapex a couple of months ago. His libido, too, has returned to normal. This is affirmed by people close to him.

"The change in him has been astounding," says Tammie Davenport, a friend. "He thinks more clearly, more rationally. He thinks, period."

Today Kanuch is homeless. He crashes some nights at Davenport's home, others at his girlfriend's place in Katy. His unemployment checks have run out. He's had no health insurance since last June, and relies on the nonprofit Houston Area Parkinson Society for free Parkinson's medication. He lives on food stamps and small loans from friends.

Kanuch remains haunted by his experiences from the last few years. But he's fueled by a desire to help people. Poverty has humbled him, reminding him of his youth spent in a public housing project in Austin.

He's dedicated to regaining his self-respect, a meaningful job, forgiveness from friends and lovers. In short, he wants his life back.

"I feel ashamed of much of the stuff I've done," he says. "I'm ashamed of having been a gambler. I'm ashamed of having been persistently sexually compulsed to do things. I'm ashamed of my job performance."

He's particularly troubled by the attempted rape, which he "vaguely remember[s]."

"I was cold, I was hurting," he says. "I was desiring warmth and human touch."

Many friends have turned their backs on Kanuch. They accuse him of making up excuses for his behavior.

He's tried to respond to their skepticism. To explain what it was like being on Mirapex. But he can't find the words to persuade them.

He hasn't yet been able to forgive himself for his behavior. But he trusts that will happen over time.